1. Field of Invention
This invention relates to substituted polybenzimidazole products and a process for their production. More particularly, this invention relates to sulfoalkyl derivatives of hydroxyethylated polybenzimidazole polymers and a process for their production.
2. Prior Art
Polybenzimidazoles are a known class of heterocyclic polymers which are characterized by a high degree of thermal and chemical stability. Processes for their production are disclosed, for example in U.S. Re. 26,065 and U.S. Pat. Nos. 3,313,783, 3,509,108, 3,555,389, 3,433,722, 3,408,336, 3,549,603, 3,708,439, 4,154,919 and 4,312,976 (all patents discussed herein are incorporated by reference). Polybenzimidazole polymers have been formed into membranes, ultrafilters, reverse osmosis devices and other types of separatory media of great utility.
While polybenzimidazole polymers are generally resistant to reaction, reaction at the imidazole nitrogen-hydrogen bond occurs under certain conditions. One method of limiting this reactivity of polybenzimidazole polymers is to chemically modify the polymer. For example, U.S. Pat. Nos. 4,020,142 and 4,154,919, disclose polybenzimidazole polymers which have been crosslinked to remove the reactive nitrogen-hydrogen bond on the imidazole ring.
In another effort to reduce the chemical reactivity of polybenzimidazole polymers, the hydrogen bonded to the imidazole nitrogen has been replaced by less reactant substituents. For example, U.S. Pat. No. 3,578,644 discloses an hydroxyl substitution on the polybenzimidazole polymer prepared by the reaction of an omega-halo-alkanol or 1,2-alkylene oxide with the polybenzimidazole polymer. See also, U.S. Pat. No. 4,599,388 which discloses a different process for the production of hydroxyl substituted polybenzimidazole polymers. However, neither of these patents disclose substituted hydroxyethylated polybenzimidazole polymers, in general, or sulfoalkyl-substituted hydroxyethylated polybenzimidazole polymers, in particular.
U.S. Pat. No. 3,943,125 discloses various substituted polybenzimidazole polymers produced by the reaction of substituted tetraamino pyridines or their acid salts with a suitable acid halide or dianhydride. While the patent broadly discloses a large number of substituted tetraamino compounds, it fails to disclose the process for their preparation. It also specifically fails to disclose sulfoalkyl-substituted hydroxyethylated polybenzimidazole polymers or a process for their production.
U.S. Pat. No. 3,518,234 discloses a process for the preparation of N-aryl substituted polybenzimidazole polymers. However, the substituted polybenzimidazole polymers are not produced by direct reaction with a polybenzimidazole polymer and substantial heating of the reaction vehicle is necessary. Further, no sulfoalkyl derivatives of substituted polybenzimidazole are disclosed.
Technical reports published by Celanese Research Company (AD-755356, dated January, 1974) and Fabric Research Laboratories (AFML-TR-73-29, dated December, 1971) disclose a process for sulfonating polybenzimidazole fibers in order to reduce their thermal shrinkage. However, these reports do not disclose a process for sulfoalkylating substituted polybenzimidazole by the process of the instant invention.
It is therefore an object of this invention to produce novel substituted hydroxyethylated polybenzimidazole polymers.
It is another object of this invention to produce substituted hydroxyethylated polybenzimidazole polymers which exhibit a high degree of resistance to chemical reaction and which are stable at high temperatures.
It is an additional object of this invention to produce a sulfoalkyl hydroxyethylated polybenzimidazole polymer using an hydroxyethylated polybenzimidazole polymer as the precursor polymer.
These and other objects as well as the scope, nature, and utilization of this invention will be apparent to those skilled in the art from the following detailed description and appended claims.